Water vessel with stern propulsion

ABSTRACT

Fast boats create a water resistance that has a detrimental effect on the consumption of fuel. The object of the present invention is to reduce the water resistance to a minimum by meansf of an arrangement that automatically adjusts the direction of the propulsion force and the trimming planes so that minimum water resistance is obtained.

[0001] The present invention relates to a water vessel with stern propulsion. The water resistance is a significant consideration for such vessels in that the higher the water resistance is the higher the consumption of fuel will be. It is therefore desirable to reduce the consumption of fuel to the lowest possible level.

[0002] The object of the present invention is to create an arrangement that can influence the direction of the propulsion force and also influence the adjustment of existing trimming bodies. The positions of said three units are transmitted to the arrangement and the arrangement also has information about the speed of the propulsion force. By influencing the trimming bodies and adjusting the propulsion force the water resistance of the vessel is reduced to the lowest possible level. Further, there is a gauging instrument for said settings. The minimum level of water resistance for different speeds of propulsion can be determined by tests. The tests can then be used in a computer program so that the arrangement automatically adjusts settings to achieve minimum water resistance for each speed.

[0003] The present invention will be further described in connection with the accompanying drawings, in which

[0004]FIG. 1 shows a high-speed water vessel,

[0005]FIG. 2 shows schematically the stern part of the vessel with a trimming body and its adjustment unit, and

[0006]FIG. 3 shows the stern part of the vessel with stern propulsion and its adjustment unit.

[0007] The drawings show a water vessel 1, having two trimming bodies 2 and 3 that are pivotably arranged about the stern part 7, as clearly illustrated in FIG. 2. Adjacent to the stern part 7, the trimming body has a conventional auxiliary device that enables the trimming body 2 to be pivoted up and down and an adjustment unit 4 has duly been arranged for this purpose. This can be a hydraulic cylinder, for instance. Alternatively, another known actuator that can be remote-controlled so that the trimming body 2 obtains a movement up and down can be used. Two trimming bodies 2 and 3 are shown in the drawings, but a large number of variations are conceivable with respect to the number and placement of trimming bodies.

[0008] The water vessel 1 has stern propulsion, that is a rudder and propeller forming a unit that co-operates with the adjustment unit 5 that can be pivoted about a substantially vertical axis and, likewise, about a substantially horizontally axis. The positions of the trimming bodies 2 and 3 and of the stern propulsion 8 are transmitted to a central unit 6. Information about the speed of the water vessel is sent to this central unit 6. The stern propulsion 8 can be provided by an inboard or an outboard motor.

[0009]FIG. 3 shows that the propulsion occurs by propeller drive, but it is also conceivable to substitute jets of a desired kind, such as air jets or water jets, for the propeller drive. The settings for the trimming bodies and the stern propulsion that provide the least water resistance can be ascertained by manual testing at different speeds. Such testing can take place for each individual vessel. The testing results can be programmed and fed to a computer arrangement that automatically adjusts the trimming bodies and the stern propulsion so that they assume positions providing the least water resistance. 

1. A water vessel (1) with stern propulsion (8), such as propeller drive or jet drive, and preferably provided with one or more movable trimming bodies (2 and 3), such as trimming plates, characterized in that, during operation of the water vessel (1), an arrangement strives to influence the same in such a way that minimum water resistance is obtained.
 2. A water vessel as claimed in claim 1, characterized in that the arrangement includes an adjustment unit (4) for each trimming body (2 and 3) and, further, an adjustment unit (5) for the direction of the stern propulsion (8).
 3. A water vessel as claimed in claim 2, characterized in that all the adjustment units (4 and 5) are connected to a central unit (6) for influencing the adjustment units (4 and 5) so that minimum water resistance is obtained.
 4. A water vessel as claimed in claim 3, characterized in that position data regarding speed, stern propulsion (8) and trimming bodies (2 and 3) are supplied to the central unit (6).
 5. A water vessel as claimed in any one or more of the preceding claims, characterized in that each trimming body (2 and 3, respectively) is pivotable about the stern part (7).
 6. A water vessel as claimed in any one or more of the preceding claims, characterized in that the stern propulsion (8) is pivotable about a central point in a downwardly-directed plane, such as a vertical plane.
 7. A water vessel as claimed in any one or more of the preceding claims, characterized in that the central unit (6) adjusts the stern propulsion (8) and one or more trimming bodies (2 and 3) based on the position data so that minimum water resistance is obtained during operation.
 8. A water vessel as claimed in claim 7, characterized in that the central unit (6) includes a control system such that said minimum water resistance is obtained, which control system can include a programmed computer unit. 